This invention relates to a smoke purifier apparatus for chimneys and the like, having an intake, a suction chamber for additional air, a combustion chamber located downstream of said intake and said suction chamber, an igniter member arranged within said combustion chamber and including a thermic element heated to a high temperature, and an outlet connection extending downstream of said combustion chamber.
It is known that both the civil and the industrial chimneys deliver smokes wherein, along with ash and other solid residual combustion products, there are contained some substances (such as carbon monoxide, unburnt hydrocarbons and nitrogen oxides) which result from an incomplete combustion, and some substances (such as sulphur dioxide) which result from the combustion of impurities contained in the fuel material by which the smokes are produced. All these substances heavily contribute to the ambient pollution and to the soiling of the discharge ducts of the chimneys. Moreover some of these substances, such as nitrogen oxides and sulphur dioxide, by combining with water produce highly corrosive acids. Therefore it is required that the smokes delivered by the civil and industrial chimneys are depurated, both in order to separate the solid residual substances carried by them, and in order to chemically modify at least the more polluting substances contained therein.
To this purpose some apparatuses have been proposed, such as electrostatic separators, liquid flow separators, filters, cyclones, gas supplied afterburners and catalytic afterburners. However, in most cases the installation and management costs of such purifier apparatuses are unsustainable, whilst on the other hand their effectiveness is not satisfactory in the general applications.
The Italian Patent No. 1,159,607 proposes a purifier apparatus for chimney smokes, with an intake for smokes, an annular suction chamber for additional air surrounding the intake, a fan acting onto the whole cross section of both the intake and the annular air suction chamber, a combustion chamber extending downstream of said fan, an igniter member arranged within the combustion chamber and including a thermic element heated to a high temperature, filter means located at the outlet of the combustion chamber, and means for collecting the solid residual substances separated by the filter means. In this apparatus, the passages for smoke and for additional air join one another upstream of the fan, and the igniter member is formed by a reflecting hollow member of stainless steel which concentrates internally of itself the heat radiating from the included thermic element. By the Italian Patent No. 1,184,021 this apparatus has been improved, particularly with respect to the fan means.
Such improved apparatuses are considerably progressive with respect to the former state of art, and they ensure a satisfactory operation in normal conditions. However they still have some disadvantages which are revealed mainly at start and in transient operation conditions, due to the inertia of the fan means. These latter, if they are not driven by a motor but only by the gas flow, start operating or accelerate with some delay before actuating an effective air suction. Therefore some smoke reflux through the air suction chamber can sometimes take place.